Buying champagne/sparkling in Paris

We are staying in a rental in the 2nd arr., just north of rue Montorguiel, in June. I am a champagne/sparkling wine fan and am looking for suggestions of where I could buy bottles to enjoy back at the apartment. Are there liquor stores or wine shops I should look for? Can you buy bottles of wine at stores like Monoprix? I am not interested in splurges necessarily, but a variety of options to sample. Thanks in advance for any suggestions you can make!

The basic generic (industrial) Champagne can be bought at monoprix and wine store chains like Nicolas.

For better Champagne and sparkling wine (crémant, ...) and not necessarily more expensive, better check the smaller wine marchants (cavistes), there are many in the city, just google for "caviste paris rue montorgueil" )for example.

There is absolutely no shortage of places to buy Champagne in Paris! As has been said, Nicolas is a good wine shop chain and they usually have a little bar in them. We actually buy rather cheap vin moussant as we drink quite copiously, in Paris we start our day off with it and it's pretty good, most supermarkets have it.